The present invention relates to a supporting structure for a commercial motor vehicle, in particular for a truck including two spaced longitudinally extending frame members between which a drive unit with an internal combustion engine and a transmission is supported and which includes an independent front wheel suspension with upper and lower control arms.
A support structure of this type is disclosed, for example, in DE 42 34 138 A1 and has two spaced vehicle frame members extending parallel to each other in the longitudinal direction of the vehicle. Between these longitudinal frame members, a drive unit including an internal combustion engine and gearbox is arranged in a front region of the support structure. The support structure includes an independent wheel suspension with upper A-arms and lower A-arms for two supporting front-axle wheels. A front cross-member and a rear cross-member are fastened to the longitudinal frame members in front and behind the front axle, with regard to the longitudinal direction of the vehicle, and a first and a second strut of the lower A-arm are mounted on the cross-members, at each side of the vehicle. The upper A-arms are mounted by their struts each on one of the longitudinal frame members. At their front end, with regard to the longitudinal direction of the vehicle, the longitudinal members are each extended forwardly by means of a support console, to which a lower front cross-member is connected which protrudes forwards beyond the support structure and forms an under-ride guard for the vehicle. In addition, each longitudinal member has a front and a rear driver""s cab bearing, so that a driver""s cab of the commercial vehicle is supported on the longitudinal frame members of the support structure via four driver""s cab bearings.
DE 198 09 209 A1 discloses a further support structure having two longitudinal members, in which a cross-member connects the front ends of the longitudinal members to each other. Furthermore, a transverse yoke is provided on the outside of the longitudinal members and a rear strut of a lower A-arm is mounted by its inner end on this transverse yoke, at each side of the vehicle. A front strut of the lower A-arm is then mounted by its inner end on the above-mentioned cross-member. At each side of the vehicle a spring element and/or shock absorber element is supported by its lower end on the lower A-arm and by its upper end on a bracing console which is formed on the transverse yoke.
DE 42 28 314 A1 discloses a three-part support structure which comprises a central support framework, a bracket-shaped front frame and a frame-type cross-bracing structure of the longitudinal members which supports the upper body parts. The central support framework extends around a drive unit including an internal combustion engine and a transmission, which is arranged essentially between the front wheels and has a downwardly open shape. The central support framework has a rear part, which is arranged behind the front axle with regard to the longitudinal direction of the vehicle. The support framework is in the form of a surrounding tubular frame and is closed by an upper cross-member. Side parts are welded onto this rear part, at both sides of the drive unit. The side parts being are formed by tubes extending approximately horizontally forwardly from an upper end of the rear part and being angled downwards before the front axle and ending approximately level with the lower end of the rear part. In order to stiffen the central support framework, the side parts are additionally connected to the rear part via struts. The upper and lower A-arms and spring elements and/or damper elements of the individual wheel suspensions are respectively mounted and supported on the central support framework.
It is the object of the present invention to provide for a support structure of the type mentioned initially, an arrangement which ensures a firm and rigid positioning for the components of the individual wheel suspension parts.
In a support structure for a commercial motor vehicle, having two spaced longitudinal frame members between which a drive unit including an internal combustion engine and a transmission is arranged and wherein the support structure has an independent wheel suspension each with an upper A-arm and a lower A-arm mounted to the support structure for supporting two wheels, a support unit is provided which, in front and behind a space for receiving the drive unit extends around the longitudinal frame members, which is fastened to the longitudinal frame members and on which at least the lower A-arms are mounted.
The invention is based on the general concept of mounting or supporting the individual wheel suspensions, or at least components thereof, on a support unit which extends all around the longitudinal frame members in the front regions thereof. By means of this design, the support structure can be provided with relatively high rigidity, in particular torsional rigidity, in the front region. As a result, the components of the individual wheel suspension, for example A-arms, which are mounted and supported in the front region and, particularly, the components which are mounted and supported on the support unit, are positioned relatively rigidly with respect to one another, so that the steering geometry operates particularly reliably during operation of the vehicle. This is of significance particularly for the steerable front-axle wheels in order to minimize wear of the suspension components and tires and to increase the vehicle safety.
According to a particularly advantageous embodiment, the support unit can have an annularly closed, ring-type front bulkhead which extends around the longitudinal frame members in front of the internal combustion engine, an annularly closed, ring-type rear bulkhead which extends around the longitudinal frame members behind the internal combustion engine, and an upwardly open lower shell which connects the front ring-type bulkhead to the rear ring-type bulkhead below the internal combustion engine, the lower shell being fastened in the region of its upper longitudinal edges to the longitudinal frame members. By means of this measure, the front region of the support structure obtains particularly high torsional rigidity, since the completely closed ring-type bulkheads can absorb torsional forces particularly well. Furthermore, the lower shell brings about an additional stiffening of the support unit and of the front region by means of a corresponding shaping, in particular by means of ribs, grooves or corrugations,
In one embodiment, a transverse yoke, which surrounds the lower shell, can be inserted in a shape-integrated manner into the lower shell and can be fastened thereto. A first strut of the lower A-arm is then mounted at its inner end on this transverse yoke at each side of the vehicle between the front ring-type bulkhead and the rear ring-type bulkhead such transverse yoke may be designed as a highly rigid component. The form-fitting connection to the lower shell enables the forces acting on the transverse yoke to he transmitted in a particularly favorable manner to the lower shell and therefore to the support structure.
In another embodiment, the support unit may have a plurality of driver""s cab bearings via which a driver""s cab of the vehicle is supported on the support unit. In this way, the geometry of the longitudinal members can be selected independently of the driver""s cab, so that more design freedom for forming variants is provided. Furthermore, a particularly high stability and rigidity of the support unit is provided which provides for good support of the driver""s cab.
Further important features and advantages of the invention will become apparent from the following description of the invention on the basis of the accompanying drawings.
Preferred exemplary embodiments of the invention are illustrated in the drawings and will be explained in greater detail in the following description where identical or functionally identical components are indicated by the same reference numerals.